The present invention relates generally to industrial process transmitters. More particularly, the present invention relates to a flow meter or pressure sensor that couples to the industrial process transmitter.
Industrial process transmitters couple to industrial process equipment and/or conduits and are adapted to measure process variables such as pressure, mass flow rate, volume flow rate, temperature and the like. The process transmitter receives a signal from a sensor that indicates a value of the process variable and sends the signal corresponding to the value of the process variable to a control panel typically via a two-wire loop. Frequently, such transmitters draw power from a two-wire loop that carries an energy-limited loop current, which varies within a range of 4-20 mA.
There are many process flow sensors that are positioned within a main process line that create a pressure drop across the flow sensor. The differential pressure across the flow sensor is correlated to a flow rate. Examples of flow meters that correlate a pressure drop to a flow rate include an orifice plate and a venturi tube.